Thickness cracks in R.C. hyperbolic cooling towers

Imprecise construction work might cause imperfection in the shell of R.C. hyperbolic cooling towers. By considering the three directions concrete fracture model and by using elements in finite element analysis which could crack in three directions, it could be shown that in imperfect shell, the thickness cracks occur at the end of the weight and thermal loads. In the other words, the inside and outside of the concrete shell separate. The number of such cracks rises up by increasing the imperfection in the cooling tower shell. This increase in the number of cracks could multiple when two concavity and convexity imperfections happen consecutively. Since there is not any reinforce bar for preventing of such cracks, so it must be avoided by precise construction work and by modifying the participating thermal load factor in combining loads